SAN FRANCISCO – If you're a baseball fan looking to add a new pastime to your vacation itinerary, consider setting a goal to visit all 30 of the sport's major league stadiums.

I began my crusade about five years ago, joining a growing number of other zealots making the pilgrimage to baseball's cathedrals.

It has become such a popular pursuit that you can buy baseball-stadium maps to document where you have been and plot where you still need to go. The one decorating my den shows I'm halfway through my odyssey, with 14 more fields of dreams still to be seen. If you need more memorabilia, there's also a book called "The Major League Baseball BallPark Pass-Port" that provides tips about each stadium, with slots to file ticket stubs and a place to "validate" each visit with a rubber stamp.

But all you really need is a love of baseball and a passion for exploring new places to relish this journey.

All the baseball teams are based in major U.S. cities and many of the stadiums are situated in bustling downtown areas with engrossing things to do and savory places to eat when you aren't attending a game. These attractions should help the cause of baseball fans trying to recruit a spouse or other traveling teammates who may not appreciate the sublime pleasures of the game.

My baseball tour already has introduced me to things that wouldn't have been on my radar if I hadn't booked a trip to see a stadium.

When I went to St. Louis to visit Busch Stadium in 2010, I rented a car one day and made the two-hour drive to Samuel Clemens' childhood home in Hannibal, Missouri, the Mississippi River village that inspired Mark Twain's best-known books about the childhood adventures of Tom Sawyer and Huckleberry Finn. The Hannibal visit had a ripple effect when I went to Boston to see Fenway Park, prompting me to rent another car to drive to Hartford, Conn., to visit the custom-built home where he spent the happiest and most productive years of his adult life. Back in Boston, I also made the short trip across the Charles River to Cambridge to check out Harvard University, and wound up stumbling upon the home of poet Henry Wadsworth Longfellow, where George Washington also lived for a short time.

When I went to Baltimore to see a game at Camden Yards, I took a water taxi out to Fort McHenry in the Chesapeake Bay to tour the site where Francis Scott Key watched American troops in 1814 successfully thwart an all-night fusillade by English ships. The heroics at Fort McHenry inspired Key to write the ode that became the country's national anthem.

Many of the stadiums are landmarks in their own right. My favorite stops so far have been baseball's oldest stadiums, Fenway Park (opened in 1912), and Wrigley Field (originally known as Weeghman Park when it opened in 1914) in Chicago. Both are located in wonderful neighborhoods that turn into street festivals during the three or four hours leading up to the game.

The stadiums of more recent vintage all have their merits too, largely because so many were built to evoke a sense of nostalgia. This retro movement started in 1992 when Baltimore's Camden Yards opened and has carried over to just about every one of the 22 baseball stadiums that have opened since then (while I haven't been to them yet, I understand Florida's two big-league ballparks are notable exceptions to this trend).

Most of the newer stadiums boast signature features designed to set them apart. Even one of the Florida stadiums, Marlins Park, added distinctive flair by building a 450-gallon (1,700-liter) saltwater aquarium behind home plate. Chase Field, the Phoenix home of the Arizona Diamondbacks, features a swimming pool behind the right field fence. Coors Field, the Denver home of the Colorado Rockies, features small trees and rocks with running water — a tip of the cap to the gorgeous mountains that can be seen on the horizon from the stadium seats.

Most of the teams also set aside areas inside and outside the stadiums to pay homage to the greatest players in franchise history. I've already seen statues of Stan ("The Man") Musial in St. Louis, Ted ("The Splendid Splinter") Williams in Boston, Willie ("The Say Hey Kid") Mays in San Francisco, Walter ("The Train") Johnson in Washington and George ("Babe") Ruth in Baltimore. In case you are wondering why the Orioles honor the Bambino even though he never played for the team, it's because Camden Yards is built in an old neighborhood that once included a bar owned by Ruth's father (the home where the Babe was born is still standing, just a short stroll from Camden Yards).

When drawing up your travel plans, strive to arrange your stadium visits so they coincide with your favorite team's trips to the same destinations.

My favorite stadium sojourns so far have included my favorite team, the Oakland Athletics. Those trips gave me a chance to wear my green-and-gold Athletics' gear in hostile territory, which has led to lively repartee with the fans of the local team. What's more, your favorite team will appreciate seeing some friendly faces, so much so that they may be even more accommodating than usual with requests for autographs and baseballs. In a further show of support, try to get tickets behind your team's dugout on the road. Just keep in mind the location of visitor's dugouts vary from stadium to stadium, so double-check before buying tickets (the visitor's dugout is on the third-base side of the field at 18 stadiums and on the first-base side at the other 12).

After each visit to a baseball stadium, I can hardly wait to go to another one. Despite my ardor, completing the journey has been a multiyear process because, like most baseball fans, I don't have the time or money to see all the stadiums in a single season. Last year, I made it to four stadiums for the first time, a new single-season record for me. Other vacation commitments this year are likely to restrict me to a single stadium: Kauffman Stadium in Kansas City, Mo., when the Athletics play there in July.

When I finally cross off the final big-stadium off my list in a few years, I am going to have to find a new quest. Well, I hear there are lots of quaint minor-league baseball stadiums located in rustic towns all across America...